In view of protecting the environment, fuel vapor has been controlled besides the exhaust emission control. According to the regulation established by the Environmental Protection Agency (EPA) and the California Air Resourced Board (CARB), a leak detection of the fuel vapor from a fuel tank is required.
A conventional leak check module for fuel vapor has a pump generating pressure gradient between an inside and an outside of the fuel tank, and a motor driving the pump. The fuel vapor leak check module, which is referred to as the leak check module, has a canister port which connects to the fuel tank through a vapor storage canister and an atmospheric vent port which communicates with the atmosphere. A switching valve connects the pump alternatively with the canister port and the atmospheric vent port, by which the fuel vapor leak check is conducted.
However, in the conventional leak check module, the centerline of the canister port is orthogonal to the centerline of the atmospheric vent port. When the canister port and the atmospheric vent port are opened parallel in the leak check module, the conduits connected with these ports are bended at middle or the other end thereof. Thus, a large space is necessary to provide the leak check module and the like on a vehicle. Furthermore, the leak check module on the vehicle is connected with the canister through a conduit which requires a space.
On the other hand, the leak check module is disposed at the vicinity of the fuel tank for detecting the fuel vapor leaking from the fuel tank so that the vicinity space of the fuel tank is restricted. As the result, when a lager space is reserved for the leak check module, the configuration of the vehicle may be changed, for example, the fuel tank may be downsized.